The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Electric printing systems typically include a series of printheads that selectively deposit fluid material onto a workpiece such as a substrate. The printheads and/or substrate may be moved relative to one another to form a pattern of fluid material on a surface of the substrate having a predetermined configuration. One such system is a piezoelectric microdeposition system (PMD) that deposits fluid material on a surface of a substrate by selectively applying electric current to a piezoelectric element associated with a printhead of the PMD system.
Conventional PMD systems may include a drop analysis system associated with respective printheads of the PMD system to ensure that the liquid material deposited from each printhead includes a predetermined shape and/or volume. Controlling the shape and volume of the fluid material deposited by each printhead controls the pattern of fluid material formed on the surface of the substrate.
Conventional drop analysis systems include large diameter lenses and illuminators that are typically located about 30 to 120 millimeters from the drop location of the fluid material to provide sufficient clearance between the printheads of the PMD system and associated mounting hardware of the drop analysis system. Therefore, conventional drop analysis systems are cumbersome and difficult to arrange properly relative to the PMD system.
Typically, drop analysis systems use a light emitting device (LED) and a diffuser screen that cooperate to illuminate drops as they are ejected from the printheads of the PMD system. Interaction between light from the LED and the drop from the printhead illuminates a profile of the drop, which may be captured by a camera. Conventional systems typically require a long-light pulse (i.e., 2 to 5 USEC) from the LED to achieve sufficient illumination of the drop in order for the camera to capture a high-contrast image. Because the drops are released from each printhead at a high speed of ejection (up to 8 meters per second), the long-light pulse of the LED may result in a “blur” of the drop. For example, a 2 USEC pulse may cause an image of the drop captured by the camera to blur by 16 microns (almost 50 percent of the size of the drop itself). Such blurring results in greater uncertainty in the true area and diameter of the drop and results in single drop readings that vary by as much as five percent. Conventional systems can achieve one percent accuracy in measuring drop volume, but can only achieve such accurate readings by taking many image samples, thereby increasing the complexity and cost of the drop analysis system.